Various forms of chain saw bar adjusting mechanisms for lengthwise adjusting a chain saw bar in order to properly tension the associated saw chain heretofore have been provided. Examples of various forms of bar adjusting mechanisms including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 2,624,379, 2,765,821, 2,839,097, 2,910,099, 3,636,995 and 4,129,943.
However, most of these previously known forms of chain saw bar adjusting mechanisms are subject to malfunction if the clamp screws or bolts for the chain saw bar become partially loosened as a result of chain saw vibration. Accordingly, a need exists for an improved form of chain saw bar adjusting mechanism which will be operative to maintain chain saw bar adjustment and to withstand chain saw vibration without damage in the event of partial loosening of the chain saw bar adjustment clamping screws or bolts.